* Companies have 30 days to comply
* Failure to comply carries penalties of $245 mln a day
* Report on November oil spill helped win ruling-prosecutor
* Chevron says plans to appeal ruling
RIO DE JANEIRO, Aug 1 (Reuters) - A Brazilian court ordered Chevron Corp and Transocean Ltd to suspend all oil production and transport operations in Brazil within 30 days, the public prosecutor's office said.
Failure to comply with the injunction, issued on Tuesday, carries penalties of up to 500 million reais ($245 million) a day.
The injunction, issued by the Specialized Bench of Brazil's 2nd Region Federal Court, was based on a request by the public prosecutor's office in the wake of a November oil spill in Chevron's offshore Frade Field northeast of Rio de Janeiro.
The prosecutor's office had appealed a decision by a Brazilian judge who refused to issue an injunction in April.
Chevron, the No. 2 U.S. oil company, said in a e-mailed statement that it plans to appeal the ruling.
Transocean, the world's largest offshore oil-rig operator, said it has a strong case and will use "every legal means necessary to prove it."
Chevron operates only one oil field in Brazil. Transocean operates about 10 drilling platforms in the country for companies such as Chevron and Petrobras, Brazil's state-led oil company and main producer.
If upheld, the injunction could result in the shutdown of Brazilian drilling operations in fields using Transocean rigs, disrupting efforts by Brazil to expand oil output.